This invention relates generally to turbochargers, and more specifically, to motor-assisted turbochargers for locomotives.
Conventionally, turbochargers are operably connected to an internal combustion engine in which exhaust gas from the engine is utilized to increase the pressure of air above ambient to the engine. Typically, the turbocharger includes a shaft, a driving turbine or expander attached at one end of shaft, and a compressor attached to the other end of the shaft. The expander is attached to the engine to receive exhaust gases from the engine and the compressor is attached to an air intake manifold of the engine.
During operation, the expander receives exhaust gas which causes the shaft to rotate, which in turn, causes the compressor to rotate and supply air to the air intake manifold of the engine at an increased pressure, i.e., at a pressure greater than ambient air pressure.
Some turbocharger systems have incorporated a separate electric motor/alternator connected to the shaft to increase the rotational speed of the shaft in a continuous manner relative to and in response to the speed of the engine, to increase the rotational speed of the shaft to overcome xe2x80x9cturbo lagxe2x80x9d (i.e., the short period of time after increased power demand is first sensed until the rotary compressor driven by the exhaust gas turbine reaches its full power capacity), and also to extract electrical energy from the exhaust gas.
In normal operation, the propulsion system of diesel electric locomotives is typically controlled to establish a balanced steady state condition wherein a diesel engine driven alternator produces, for each discrete position of a throttle handle, a substantially constant amount of electrical power for the traction motors. The throttle typically has eight positions or notches with notch 1 being a low power level and notch 8 being maximum power level.
There is a need for a motor-assisted turbocharger for tailoring the turbocharging of a diesel engine of a diesel electric locomotive to increase engine performance and to provide auxiliary electrical power for auxiliary devices over a range of discrete power levels.
The above-mentioned need is met by the present invention which provides, in a first aspect, a method for turbocharging an engine of a locomotive in which the engine is operable at a plurality of discrete operating power levels. The method includes controlling at least one of electrical energy to a motor-assisted turbocharger at a plurality of discrete energy levels and air pressure from the motor-assisted turbocharger to the engine at a plurality of discrete air pressure levels above ambient air pressure based on at least some of the plurality of discrete operating power levels of the engine.
In a second aspect, a method for operating an engine of a locomotive in which the engine is operable at a plurality of discrete operating power levels includes controlling at least one of electrical energy to a motor-assisted turbocharger at a plurality of discrete energy levels and air pressure from the motor-assisted turbocharger to the engine at a plurality of discrete air pressure levels above ambient air pressure based on at least some of the plurality of discrete operating power levels of the engine, and controlling generation of electrical energy from the motor-assisted turbocharger at some of the plurality of discrete operating power levels of the engine.
In a third aspect, an apparatus for turbocharging an engine of a locomotive having a plurality of discrete operating power levels includes a motor-assisted turbocharger for increasing air pressure above ambient air pressure to the engine, and a controller for controlling at least one of electrical energy to a motor-assisted turbocharger at a plurality of discrete energy levels and air pressure from the motor-assisted turbocharger to the engine at a plurality of discrete air pressure levels above ambient air pressure based on at least some of the plurality of discrete operating power levels of the engine.
In a fourth aspect, an apparatus for turbocharging an engine of a locomotive having at a plurality of discrete operating power levels includes a motor-assisted turbocharger for increasing air pressure above ambient air pressure to the engine, and a controller for controlling at least one of electrical energy to a motor-assisted turbocharger at a plurality of discrete energy levels and air pressure from the motor-assisted turbocharger to the engine at a plurality of discrete air pressure levels above ambient air pressure based on at least some of the plurality of discrete operating power levels of the engine, and the controller being operable to control generation of electrical energy from the motor-assisted turbocharger at some of the plurality of discrete operating power levels of the engine.
In another aspect, a portion of a power plant for a locomotive includes a diesel engine and the apparatus as described above for turbocharging the diesel engine.